This invention relates to a specified geometrical isomer of 4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-methylpiperidine-N-oxide (hereinafter referred to as .beta.-cyproheptadine N-oxide) as an appetite stimulant; also contemplated within the scope of the present invention are pharmaceutically acceptable acid addition salts thereof. Further, this invention relates to processes for the preparation of such compounds; to pharmaceutical compositions comprising such compounds; and to methods of treatment comprising administering such compounds and compositions when an appetite stimulant is indicated. The free base form of the .beta.-cyproheptadine N-oxide of the present invention has the following structural formula I: ##SPC1##
Unexpectedly it has been discovered that isomeric resolution of 4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-methylpiperidine-N-oxide provides a geometrical isomer (.beta.-cyproheptadine N-oxide, characterized below) which is an appetite stimulant substantially devoid of unwanted side effects such as the antiserotonin activity of the unresolved, naturally occuring isomeric mixture. (.alpha. and .beta. forms). Said isomeric mixture is generically disclosed in U.S. Pat. No. 3,014,911 Dec. 26, 1961) to have antiserotonin and antihistamine activity.
Accordingly, it is an object of the present invention to provide .beta.-cyproheptadine N-oxide and its pharmaceutically acceptable salts as appetite stimulants in a form substantially free (less than 15 wt. % contamination) of its corresponding .alpha.-geometrical isomer (hereinafter characterized). It is a further object of this invention to provide processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when an appetite stimulating effect is indicated.